Background of the Invention -
[0001] 1. Field of the Invention. The present invention relates to the electronic control
of glass forming machines and more particularly, to the precise and programmable control
over at least some of the components of an individual section glass forming machine.
[0002] 2. Description of the Prior Art. Typically a glass forming machine comprises a plurality
of individual sections which perform identical functions only at a phase differential
between each other. Each section includes a plurality of cyclically moving components
which are pneumatically activated to perform the respective steps in a glass forming
process. Although the basic glass forming steps have undergone very little change
over the past decades, highly sophisticated control systems have evolved to control
the execution of these steps thereby allowing increased production speed, greater
reliability, reduced waste, closer tolerances in produced ware and greater speed in
setting up a machine for a change in job.
[0003] One aspect all individual section machines have in common is that the pneumatically
activated components are controlled through a plurality of associated valves which
are generally located in a valve block. The activation of the valves in the block
has typically been effected by a mechanical timing drum driven in synchronism with
a gob feeding mechanism. Respective projecting cam members are disposed in annular
grooves in the drum surface and mechanically cooperate with the valves to effect their
respective activation and deactivation. Relative timing between events in the machine
cycle are adjusted by the relative position of the respective cam members in the annular
grooves. For a basic description of such a glassware forming machine, reference is
made to U.S. Patent No. 1,911,119 issued May 23, 1933 to H. W. Ingle.
[0004] Electronic sequencing of the respective elements of the glass-ware forming machine
is now emerging. For a description of electrically controlled glassware forming machinery
reference is made to U.S. Patent No. 3,762,907, issued October 2, 1973 to Quinn and
-' Kwiatkowski, and U.S. Patent No. Re. 29,642, reissued May 23, 1978 to Kwiatkowski
and Wood (both commonly assigned with the present invention). Briefly, in electronically
controlled glassware forming machines activation signals are generated by an electronic
controller to selectively activate or deactivate solenoid operated valves to effect
timed operation of the components which perform the glassware forming steps. These
electronic controllers provide much more precision in the respective time in a cycle
that a valve is activated and allow small adjustments in such times to be easily made.
Also job changes, where the complete timing of almost all components is altered, are
quickly and easily made. The more sophisticated modern controllers function similarly
to these controllers but use digital computers to further enhance operator interface
with the machine and provide a variety of other convenience features. Although the
glass forming art has been considerably forwarded by such devices, their main limitation
is that they can only provide an activation or deactivation signal at a given time
in a cycle. They exert no control over the actual motion envelope of the respective
component.
[0005] As those skilled in the art will appreciate, there are certain steps in the glass
forming process where the motion of the component must be precisely controlled if
acceptable ware is to be produced. Furthermore, the desired motion of such components
may vary depending on the job. For example the invert of a parison from the blank
side to the mould side must be smoothly accomplished at a given speed or the acceleration
forces on the parison will result in a deformation of the soft glass. Bigger ware
requires a slower speed as the centrifugal forces are greater, and a job change from
smaller to bigger ware will require a change in the speed of the component which effects
the revert step.
[0006] Presently, the motion envelope is controlled to a great extent through dampening
of the individual pneumatic cylinders and by con- , trolling the flow of air from
the cylinders on their exhaust strokes- to limit their speed of movement. One method
of speed control is executed in the valve block. Activation of a solenoid valve allows-
air to flow through a one-way check valve in the valve block to the pneumatic cylinder
thereby extending the cylinder. When the valve is deactivated and the component is
returned to its original position, the one-way check valve closes and the air is forced
to flow through an adjustable needle valve in the valve block. The needle valve may
be adjusted to limit the flow of air from the pneumatic cylinder on the exhaust stroke
and correspondingly limit the speed of the cylinder. Many of the components on a glass
forming machine are activated through double-acting cylinders. The speed of such components
is also affected by the air pressure connected to the valve. An example of a state
of the art valve block which is adapted for electronic control is disclosed in Lowe,
U.S. Patent No. 4,293,004 which is herein incorporated by reference. The Lowe patent
is commonly assigned with the present invention. A novel approach to regulating air
pressure into the cylinder and the flow or exhaust is illustrated in Figure 1 of the
Lowe patent.
[0007] Although the L.owe valve block and other similar arrangements in conjunction with
individual dampening of the respective pneumatic cylinders and electronic control
allow a great deal of control over the motion envelope of a given component, they
have a number of drawbacks. Any changes in the range of motion of a component, although
rare, must still be individually adjusted at the machine. The controller and valve
block can only turn an air supply on and off and limit the flow of air in and out
of a cylinder. The acceleration, deceleration and velocity of a component must be
adjusted by on-the- spot trial and error. Job changes requiring a change in the motion
envelope of a component require a large degree of experimentation by the operator.
Due to the large volume of air flow even a single forming machine uses it is often
desirable to operate with unfiltered air. In the typical operation of the I.S. machine
various condensation, cylinder oil, sludge and varnish from the compressor tend to
find their way into the air lines. Such foreign materials may play havoc with the
fine adjustment of a needle valve requiring constant operator adjustment of speed
for some critical *components.
[0008] Perhaps most importantly, it is thought that precise control - - - over the motion
envelopes of at least some of the more critical components of a glass forming machine
will allow further increases in production speed, a further reduction in waste or
defectively produced containers, and possibly breakthroughs in lightweight container
technology.
Summary of the Invention
[0009] In accordance with the present invention it is proposed to precisely control the
motion envelope of at least some of the components which perform the critical steps
of the glass forming process. The present invention will allow, within negligible
tolerances, positive control over timing, acceleration, velocity and deceleration
of desired components in a glass forming machine. In a preferred embodiment the present
invention would eliminate all pneumatic cylinders in the typical glass forming machine,
the associated valve blocks and the need for a high volume source of costly compressed
air.
[0010] In its broadest aspects the present invention provides for precise and programmable
motion control over at least one of the cyclically movable components in a glass forming
machine which execute critical steps in the glass forming process. The desired component
is driven by a digitally responsive motor module which is controlled by an electronic
controller, preferably of the digital microcomputer type, which provides inputs to
said motor in accordance with stored ramping functions. The motion of a given component
may be initiated by any of the present generation electronic controllers such as that
described in U.S. Patent No. Re. 29,642 reissued May 23, 1978, to Kwiatkowski and
Wood which patent is incorporated herein by reference.
[0011] Accordingly, it is an object of the present invention to provide precise control
over the motion envelope of the components of a glassware forming machine which execute
critical steps in the forming process.
[0012] It is another object of the present invention to provide complete repeatability of
a desired motion envelope.
[0013] It is another object of the present invention to provide for remote changes in the
cushioning of a component.
[0014] It is another object of the present invention to reduce downtime for job changes
by providing for programmable control of the motion envelope of selected components
of a glass forming machine which control can be derived from past fine-tuned job histories.
[0015] It is another object of the present invention to reduce the air volume requirements
and noise of the typical glassware plant.
[0016] It is another object of the present invention to eliminate the dependence of critical
components on precise control over air pressure and exhaust.
[0017] It is another object of the present invention to eliminate the constant adjustments
which an operator must make to the critical components of a glass forming machine
due to changes in air pressure, ambient temperature and wear of the respective cylinder.
Brief Description of the Drawings
[0018]
Figure 1 is a block diagram of a prior art electronic control systems interface with
the present invention.
Figure 2 is a schematic representation of a present I.S. machine having the majority
of its components driven by digitally responsive motor modules in accordance with
the present invention.
Figure 3 illustrates data tables used in accordance with one embodiment of the present
invention.
Figure 4 is a rotation table which is required for driving the stepper motors of the
preferred embodiment.
Figure 5 is a schematic drawing of two individual function microcomputers connected
to stepper motors which may be used in the preferred embodiment of the present invention.
Figure 6 is a flow diagram illustrating a method of operating an individual function
microcomputer in accordance with the present invention where prior art electronic
control units provide control over both modes of a component's movement.
Figure 7 is a flow diagram illustrating a method of operating an individual function
microcomputer in accordance with the present invention where prior art electronic
control units provide control over only a single mode of the component's movement.
Figure 8 is a flow diagram illustrating a subroutine for controlling the direction
of a stepper motor in executing the flow diagrams of Figures 6 and 7.
Figure 9 is a flow diagram illustrating a subroutine for controlling the direction
of a D.C. or A.C. digitally responsive motor module system in executing the flow diagram
of Figures 6 and 7.
Figure 10 is a block diagram of a D.C. servo motor system which may be utilized as
a digitally responsive motor module in accordance with the subject invention.
Figure 11 is a block diagram of an A.C. servo motor system which may be utilized as
a digitally responsive motor module in accordance with the subject invention.
Detailed Description
[0019] While this invention is susceptible of embodiment in many different forms, there
is shown in the drawings and will herein be described in detail, one specific embodiment,
with the understanding that the present disclosure is to be considered as an exemplification
of the principles of the invention and. is not intended to limit the invention to
the embodiment illustrated.
[0020] Referring to Figure 1, a simplified block diagram illustrating the interface of the
present invention to prior art electronic control units is shown. Although a variety
of electronic controllers are available for controlling glass forming machines, the
preferred embodiment of the subject invention utilizes a unit comprising a dedicated
section control unit for each section of the glass forming machine as fully disclosed
in U.S. Patent No. Re. 29,642 reissued to Kwiatkowski and Wood and herein incorporated
by reference. The above patent is commonly assigned with the subject application.
[0021] As is described above in the Background of the Invention, present electronic controllers,
irrespective of the particular design, all provide activation signals to selectively
activate or deactivate solenoid operated valves to effect precise initiation of movement
of the various components in an individual section machine. The basic block makeup
of such systems is shown in Figure 1 and includes an electronic control unit 17, operator
controls 15 for changing timing and starting and stopping the I.S. machine, a central
console 18 and mass storage 19 for programming and/or providing data to the electronic
control unit 17, and a pulse generator 16 for providing timing signals to the electronic
control unit in synchronization with the movement of certain components of the glass
forming machine including the plunger, shears, and molten glass distributor.
[0022] Referring to Figure 2, a simplified schematic drawing of an individual section of
a glass forming machine adopted for use with the present invention is illustrated.
The individual section is generally referenced 11 and has a majority of its components
driven by digitally responsive motor modules 13, rather than the conventional pneumatic
cylinders. As used herein, the term "digitally responsive motor modules" includes
analogue motors which are ultimately digitally controlled, such as D.C. servo or variable
frequency A.C. types which are controlled by sending stepped voltage levels to the
motor and by using conventional feedback control null- ing the motor to the new input
level.
[0023] The components of the section are schematically represented and include blank mould
21, funnel 23, baffle 25, invert-revert mechanism 27, blow mould 29, blow head 31
and takeout arm 33. The mechanical linkages between each of the motor modules 13 and
the various components are symbolized by dotted lines 14. These may be standard types
of mechanical linkages well known in the art and may include rack-and-pinion drives,
cams, direct connection to a component which rotates, gearboxes and the various other
mechanical linkages.
[0024] Present individual section glass forming machines include various other components,
such as a thimble and plunger, depending on the type of machine and the specific work
which the machine is set up to run. These variations are well appreciated by those
skilled in the art. As will be appreciated by a reading of the subject specification,
such other components may also be precisely controlled by the present invention.
[0025] Molten glass is fed to the individual section from the furnace through a mechanical
plunger, shears and distributor arrangement, all being generally referenced 20 in
Figure 2. A single set of these components will often service between 6 and 12 sections
in a glass forming machine. The individual sections are synchronized to the plunger
and shears through pulse generator 16 in Figure 1. The pulse generator may be of the
shaft encoder type or of a variety of _ _ types which provide synchronization between
the individual section components and the rest of the glass forming system.
[0026] In the preferred embodiment a plurality of component controllers or individual function
microcomputers are provided, one for each motor module, and each is dedicated to the
control of the motion envelope of a particular component of the glass forming machine.
In Figures 1 and 2 each component controller or individual function microcomputer
is illustrated as a separate block and is labeled according to the component whose
motion is controlled.
[0027] In accordance with the above the individual function microcomputer controlling the
motion envelope of the blank mould is referenced 22, the funnel 24, the baffle 26,
the invert-revert mechanism 28, the blow mould 30, the blow head 32 and the takeout
arm 34.
[0028] A prior art section electronic control unit 17 is connected to each of the component
controllers and provides signals for the initiation of movement of the various components
of the glass forming machine. The section control unit is programmable and receives
data indicative of the relative initiation times of the various components from a
central console 18, (Figure 1) which includes a mass storage device such as floppy
disks or tape drive. The individual function microcomputers are also preferably connected
to central console 18. Each individual function microcomputer includes sufficient
storage for a control program and data to provide drive signals to the digitally responsive
motor modules such that the desired motion envelope of the driven component is achieved.
[0029] Referring to Figure 5, a schematic diagram of individual function microcomputers
26 and 28 is illustrated along with said individual function microcomputers respective
connections to digital motor modules 13 which are stepper motors in the preferred
embodiment. The individual function microcomputers schematically illustrated in Figure
5 include three data tables labeled Ramp Table (X) referenced 60, Ramp Table (Y) referenced
62, and Rotate Table referenced 64. The individual function microcomputer also includes
a CPJ, 56, an output port 66, an Address Pointer X referenced 53, an Address Pointer
Y referenced 54 and a Rotate Pointer referenced 55. Inputs to the individual function
microcomputer are received on lines 35, 36 and 37 from a prior art electronic control
unit such as-17 in Figures 1 and 2. As such prior art electronic control units are
typically designed to provide a 24-volt output to solenoid valves, an optical isolater
circuit 38 is included to isolate the 24-volt actuation signal from the 5-volt computer
inputs and to further prevent interference from electrical noise spikes.
[0030] As will be explained below, some of the individual function microcomputers in the
present invention will have two inputs from the prior art electronic control unit,
such as individual function microcomputer 28, while others will only have a single
input, such as individual function microcomputer 26.
[0031] A digitally responsive motor module, referenced 13, is connected to the output of
the individual function microcomputers. As illustrated in Figure 5, the preferred
embodiment utilizes stepper motors which have four discrete coil windings 47A, 47B,
47C and 47D which are respectively energized by driver transistors QA, QB, QC and
QD. The stepper motors in actuality may have a great number of coils which are serially
connected to form four discrete groups of coil systems which may be electrically represented
as shown. The driver transistors are activated by the output of the individual function
microcomputer through optical isolation circuits 39.
[0032] As will be readily appreciated by those skilled in the art, the hardware implementation
of the individual function microcomputers may take on a variety of configurations
wherein some or all of the data tables and pointers may be external to the actual
microcomputer. It would, of course, also be possible to implement the present invention
with a large number of discrete logic chips.
[0033] Referring again to U.S. Patent No. Re. 29,642, which is herein incorporated by reference
and particularly to Figures 3 and 6 of said patent, the inputs on lines 35, 36 and
37 to the individual --function microcomputers may be derived from the flip-flop latches
referenced 76 in said patent. These latches are set upon an activation signal for
a given component from the electronic control unit. Setting of the latches results
in a continuous electrical signal of- - - +
24 volts which activates a solenoid operated pneumatic valve in - present glass forming
machines. The latches are reset upon a deact-
vation signal for said component from the electronic control unit. - The reset of the
latch turns off the signal allowing the solenoid operated pneumatic valve to return
to its closed position turning off the air supply to the cylinder.
[0034] Although the preferred embodiment of the present invention utilizes stepper motors,
as will be appreciated by those skilled in the art, it would also be possible to implement
the presnt invention with synchronous motors and variable frequency drives, or with
servo motors utilizing closed-loop feedback control.
[0035] For an example of a D.C. servo motor control system adopted for use with the present
invention, reference is made to Figure 9. A set point counter 72 is incremented or
decremented under program control of the associated individual function microcomputer.
The set point counter then outputs a new binary count to the input of a digital to
analogue converter 73 which in turn outputs a representative analogue voltage level
to a power operational amplifier 75. The power operational amplifier 75 then drives
a D.C. servo motor 78 in the proper direction to change the analogue feedback signal
from an absolute position sensor 76 until it is equal to the analogue output of the
digital to analogue converter. The absolute position sensor 76 is illustrated connected
to machine component 80 which is driven by D.C. servo motor 28 through mechanical
linkage 79.
[0036] For an example of an A.C. motor control system adopted for use with the present invention,
reference is made to Figure 10. A set point counter 83 is incremented or decremented
and a motor rotation direction flip/flop is set or reset under program control from
the associated individual function microcomputer. The set point counter then outputs
the new binary count to the input of a digital to analogue (D/A) converter 84 which
in turn outputs a representative analogue voltage level to an operational amplifier
85. The operational amplifier then drives a voltage to frequency converter 86. The
output square wave from the voltage to frequency converter 86 is then converted to
a simulated sine wave signal using a square wave to sine wave converter circuit 87.
The simulated sine wave is then amplified in a power amplifier circuit 90 and sent
to the rotor coil winding of the A.C. motor 91. The simulated sine wave is also sent
to the field coil winding of the A.C. motor 91. The signal sent to - the field coil
winding will be in phase or 180 degrees out of phase with the rotor signal depending
upon the status of motor rotation direction flip/flop 88. This determines the direction
of rotation of the A.C. motor. The motor drives machine component 92 through a mechanical
linkage 93 until a feedback signal is produced by absolute position sensor 94 which
equals the output of the digital to analogue converter 84.
[0037] The operation of the stepper motors utilized in the preferred embodiment of the subject
invention may be described by referring to the rotate table of Figure 4 and the schematic
diagram of the stepper motors in Figure 5. The values of the transistor drivers Q
are given in the columns of the table in Figure 4 for clockwise and counterclockwise
rotation of the stepper motors.
[0038] For example, if the last position of the stepper motor resulted from energization
of the drivers according to row A of Figure 4, i.e., drivers QA and QC energized and
drivers QB and QD unenergized, a counterclockwise step in rotation would result from
energizing the drivers according to row A+3 while a clockwise step in rotation would
result from energizing the drivers in accordance with row A+1 of Figure 3. It can,
therefore, be seen that the rotation of the stepper motor is controlled by the appropriate
energization of the four drivers by the individual function microcomputer in accordance
with the rotate table of Figure 4.
[0039] Presently, stepper motors are available in a variety of configurations including
electric-hydraulic stepping motors and electric-hydraulic stepping cylinders. The
motors are capable of - torques in excess of 2,000 inch pounds with a resolution over
400 steps per revolution and speeds in excess of 2,000 RPM. The cylinders, which may
essentially take the place of presently used pneumatic cylinders in the subject invention,
are available in a wide variety of stroke lengths with resolutions to .0005 inch per
step available and speeds to 300 inches per minute. It should be noted that the field
of stepper motors is being rapidly advanced with new innovations appearing on the
market frequently.
[0040] Referring to Figure 3, a data table is illustrated for con- --trolling the motion
of a digitally responsive motor module through N steps in accordance with a program
to be described. Each step of motion of the motor module is assigned two 8-bit words
in the data table. The first bit of each word is used to indicate if motion is to
be initiated, ended or to proceed in a clockwise or counterclockwise direction. For
example, if the first bit of each of the 8-bit words is 0, the individual function
microcomputer will recognize that it is at the beginning of a motion envelope, as
may be seen by the word referenced X in the Ramp Table (X) and by the words referenced
Y+N+l in Ramp Table (Y). Alternatively, if the first bit of each word is 1, as illustrated
in word X+N+I of Ramp Table (X) and in word Y of the "function off" Ramp Table (Y),
the individual function microcomputer will recognize that it has completed a motion
envelope and stop the stepper motor. The direction of rotation of the step is indicated
by placing one (1) in the. appropriate first bit of the two words. As shown in Figure
3, if a 1 is placed in the first digit of the first word, rotation will be clockwise,
while if a 1 is placed in the first digit of the second word, rotation will be counterclockwise.
The remaining 14 bits of the two words which define a single step of motion are used
to indicate a 14-bit binary number. These bits are called "rate bits" and, as will
be more fully explained below in the discussion of Figure 6, determine the period
of time before the individual function microcomputer initiates the next step of movement.
This is accomplished by cycling the microcomputer the number of times indicated by
the 14-bit number prior to reading the next two 8-bit words and proceeding to the
next step. It should be appreciated that the two data tables Ramp Table (
X) and Ramp Table (Y) are designed to be complementary and linked together. That is,
Ramp Table (X) will control the motion of the component in its first mode of movement.
Ramp Table (Y) will control the motion of the component in its second mode of movement
back to its original position. The preferred embodiment of the present invention contemplates
that there will be an identical number of steps in each mode of movement. Therefore,
in moving through the first mode of movement, each incrementation of the X table pointer
will be accompanied by an incrementation of the Y table pointer. The data referenced
X in Ramp Table (X) indicates the start position of the stepper motor while the data
referenced Y in Ramp Table (Y) indicates the end of the second mode of movement. Likewise,
the data referenced X+1 in Ramp Table (X) controls the first step of motion in the
first mode while the data referenced Y+1 in Ramp Table (Y) controls the last step
of motion in the second mode of movement. As should be appreciated by the above, the
use of such ramp tables to control the motion of the component assures precise control
over movement, velocity and acceleration. Typically, the first step will have a relatively
large rate bit number. The succeeding steps will have rate bit numbers which successively
decrease in absolute value, accelerating the component until maximum velocity is reached
in the middle of the mode of movement. The rate bit numbers will then begin to increase
in absolute value, decelerating the component, until the end of the respective ramp
table is reached and the component is stopped. Such ramp tables allow precise tailoring
of the motion envelope of the various components in a repeatable method.
[0041] As will be appreciated by those skilled in the art, the program illustrated on the
flow chart of Figure 6 is designed to be compatible with present electronic section
control units. As previously described, such control units typically function by turning
on and off various solenoid valves which allow pressurization of the pneumatic cylinders
which drive the components in the glass forming machine. Some components in the glass
forming machine, such as the funnel, baffle and blow head, are driven in one direction
and then returned by spring or other means. With these components the present electronic
control units activate a solenoid to initiate movement of the components in a first
mode. The solenoid remains activated until the appropriate time in the glass forming
cycle is reached for the component to return in a second mode of movement to its original
position. At this time the solenoid is deactivated and the component is allowed to
return to its original location by mechanical means outside the control of the electronic
control unit.
[0042] Other components, such as the invert-revert arm, blank mould, blow mould and takeout
arm, are driven in one direction, and then driven back to their original position
by either a second pneumatic cylinder or through the use of a dual-acting pneumatic
cylinder. The invert-revert arm is typically driven in both directions. For example,
in present machines the electronic section control unit activates a solenoid to allow
pressurization of a cylinder moving the invert-revert arm in the invert mode. The
electronic section control unit is timed to turn off the solenoid after the invert
mode is completed. At the appropriate point in the glass forming cycle a second solenoid
is then activated to allow pressurization of a second cylinder driving the invert-revert
arm in the revert mode back to its original position. The second solenoid would then
be turned off after the revert position is reached. To maintain positive control over
the invert-revert arm, there may be overlap between the turning off of the first solenoid
and the activation of the second solenoid.
[0043] It, of course, would be possible to specifically design a control system which would
merely initiate the individual function microcomputer and further communicate with
the individual function microcomputer should problems arise. However, to make the
present invention compatible with existing controllers, it is necessary to make use
of the existing signals from the electronic control unit to the various solenoid valves.
These signals will be present as long as the respective component is to be continued
in motion. Should problems arise, most electronic control units have methods of immediate
stopping of the machine. The present invention therefore tests for the presence of
the respective solenoid energization signal from the electronic control unit, and
should such signal stop, the subject invention will immediately stop the components.
[0044] Referring now to Figure 6, a simple flow chart is illustrated which may be used to
control the individual function microcomputers in accordance with the present invention.
This particular program is designed to control individual function microcomputer 28
which controls the invert-revert arm of Figure 1, but it may also be used to control
any of the other components which move in a cyclical manner where control over the
complete cycle is desired. With minor changes, which will be hereinafter described,
this program may also be used to control components such as the baffle and funnel
which are presently'under electronic control only in their first mode of movement.
[0045] The program is initiated at the circle "START" and immediately enters a test point
"INVERT SIGNAL PRESENT & REVERT SIGNAL NOT PRESENT" to test the input lines 35 and
36 of individual function microcomputer 28 as shown in Figure 5. These signals will
be outputted to the individual function microcomputer by the section control unit
17 of Figures 1 and 2 at the appropriate time in the cycle as further described in
U.S. Patent No. Re. 29,642. Assuming that the test is positive and the invert signal
is present and the revert signal not present, this indicates that the glass machine
is at some point in the invert mode. The test point "X TABLE AT END" is then reached
to test if the invert mode has ended. If the Address Pointer X, 53, in individual
function microcomputer 28 indicates the X table is at its end, the decision point
"REVERT SIGNAL PRESENT & INVERT SIGNAL NOT PRESENT" is reached to again test the input
lines 35 and 36 of the individual function microcomputer 28. If the electronic control
unit has not yet reached the proper time in the cycle for the revert mode to begin,
the program will be initiated again at "START" and proceed through the above decision
points. As the present invention is designed to be compatible with existing electronic
control units, this feature of the program allows the electronic control unit to continue
to output the invert signal for an indefinite time after the invert mode has been
completed without any effect on the components, which is also how a prior art pneumatic
cylinder would act upon reaching full extension and continuing to be pressurized.
[0046] If the test point "X TABLE AT END" indicates the X table is not at the end, the instruction
"INCREMENT X and Y POINTERS" is reached resulting in Address Pointer X, 53, and Address
Pointer Y, 54, being incremented to the next position in the X and Y tables. The instruc-
' tion "PERFORM X TABLE ROTATE SUBROUTINE" is then executed. The Rotate Subroutine
is illustrated in Figures 8 and 9, with Figure 8 illustrating the subroutine for a
stepper motor as above described in the preferred embodiment and Figure 9 illustrating
a subroutine for a D.C. servo motor on A.C. variable frequency motor as described
above in conjunction with Figures 10 and 11 respectively. Both Rotate Subroutines
initially cause the test "CW BIT IN X TABLE" to be performed. The CPU then executes
instructions to determine if a 1 is in the first digit of the first word in the X
Table which is pointed to by the Address Pointer X. Depending on the outcome of the
test, the instruction "INCREMENT SET POINT COUNTER" or DECREMENT SET POINT COUNTER"
is executed in the case of D.C. or A.C. digitally responsive motor systems (Figure
9) and the instruction "INCREMENT A POINTER IN ROTATION TABLE" or "DECREMENT A POINTER
IN ROTATE TABLE" is executed in the case of the preferred embodiment stepper motors
(Figure 8). The Rotate Pointer 55 in individual function microcomputer 28 is then
appropriately incremented or decremented to indicate the appropriate energization
of the drive transistors 47 for proper rotation direction as illustrated in Figure
4. With the rotate subroutine for stepper motors illustrated in Figure 8, in the case
of clockwise rotation, the instruction "IF A POINTER AT A+4 MOVE A POINTER TO A" is
performed and in the case of counterclockwise rotation, the test "IF A POINTER AT
A-1 MOVE A POINTER TO A+1" is performed. These instructions redirect the Rotate Pointer
to the proper location in the table upon reaching either end of the Rotate Table.
The instruction "SEND DATA POINTED TO IN ROTATE TABLE TO MOTOR" is then executed and
the appropriate data is then output from Output Port 66 of individual function microcomputer
28 (Figure 5) through optical isolator circuit 39 to the driver transistors QA, QB,
QC and QD resulting in energization of stepper motor coils 47A, 47B, 47C and 47D for
the desired rotation step of movement.
[0047] The digitally responsive motor module then moves through a single step of rotation
and the instruction "LOOP "R" (X Table) TIMES" is reached in the main program. "R"
(X Table) is the rate bit number pointed to in the X Table by Address Pointer X, 53,
in individual function microcomputer 28. This instruction results in continued looping,
with a test every loop to determine if the invert signal is still present and the
revert signal not present, until the number of loops equals "R" (X Table). The program
then returns to the circle "START" and is executed again.
[0048] This last instruction which provides for looping the number of times indicated by
the rate bits provides the method of controlling the speed of the digitally responsive
motors by delaying execution of the next step for the desired time period as indicated
by the size of the number making up the rate bits.
[0049] The program continues to be executed until the X Table reaches its end and the invert
mode of movement is completed. The tests are continually performed until such time
as the section control unit 17 outputs a revert signal and turns off the invert signal
on lines 35 and 36 to the individual function microcomputer 28. The test "REVERT SIGNAL
PRESENT & INVERT SIGNAL NOT PRESENT" will then be met and the program will proceed
to the test "Y TABLE AT END". If the Y Table is at an end, as indicated by a 1 in
the first digit of each of the two words occupying the location Y in the data table,
the program will be initiated again at "START". Assuming the first mode of movement
has just been completed and the X Table is at an end which is the memory location
X
+N+1 as indicated in Figure 3, the Y Table will be at the beginning for the first step
of movement in the revert mode. The test "Y TABLE AT END" will be negative and the
program will proceed to the instruction "DECREMENT X and Y POINTERS". This will result
in the execution of a set of instructions causing the Address Pointer X and Address
Pointer Y to be decremented to the respective data positions X+N and Y+N as illustrated
in Figure 3. The instruction "PERFORM Y TABLE ROTATE SUBROUTINE" will then be executed.
This will result in the execution of the individual instructions above described in
conjunction with "PERFORM X TABLE ROTATE SUBROUTINE" and Figures 8 and 9 except the
test "CW BIT IN X TABLE" will be performed on the Y Table. That is, the test will
be performed on the first digit of the first word which is pointed to by the Address
Pointer Y rather than the Address Pointer X. This subroutine will, therefore, not
be further described.
[0050] After performance of the rotate subroutine, the test "REVERT SIGNAL PRESENT & INVERT
SIGNAL NOT PRESENT" is again performed to '_ determine if the electronic section control
unit 17 is still sending signals indicating the revert is to continue. If the revert
is to. continue, the test "LOOP "R" (Y Table) TIMES" is performed in the same manner
as the instruction "LOOP "R" (X Table) TIMES" was above described except the data
"R" (Y Table) is taken from the Y table at the data location pointed to by the Address
Pointer Y. The program then returns to the START position and executes again.
[0051] Should, for any reason it be desired to stop the movement of the invert-revert arm,
the operator could push the appropriate stop button on the prior art electronic section
control unit which would turn the signal for the invert off, causing the digitally
responsive motor module to stop. Both the X and the Y ramp tables are linked together,
such that should it be necessary to stop the invert-revert arm in the middle of its
movement, the application of revert would cause the arm to move back to the initial
invert position.
[0052] The individual function microcomputers which control components such as the funnel
and baffle, i.e., components which are presently driven in one direction and allowed
to return by other mechanical means outside the control of the electronic control
unit, would function similarly with the exception that the only test performed would
be to determine if, for example, the baffle signal is present. As long as the baffle
signal is present, the individual function microcomputer will continue to operate
the digitally responsive motor module driving the baffle in accordance with the Ramp
Table (X). Conversely, if no baffle signal is present, the individual microcomputer
would assume it is desired to place the baffle back in its initiation position and
operate the baffle in accordance with Ramp Table (Y). Should the baffle activate signal
stop due to an emergency stop, the individual function microcomputer would place the
baffle back in its initial position along Ramp Table (Y) simulating the present return
by other mechanical means when air pressure is turned off to the cylinder actuating
the baffle. A simple flow""' chart is illustrated in Figure 7 for controlling the
baffle and other single-mode components.
[0053] All individual section glass forming machines must have synchronization between the
cyclical movement of the components and the glass feed to the glass forming machine.
This synchronization is often provided by the use of a conventional shaft encoder
which outputs a digital signal of 360 pulses per revolution of an appropriate shaft
on the glass forming machine. Other methods of synchronization are equally compatible
to the present invention including driving the feeder and glass forming machine with
a synchronous motor through an inverter and taking a signal from said inverter to
synchronize the control of the glass forming components.
[0054] To make the present invention easily adaptable to a variety of different types of
glassware without changing all rate bits, the individual function microcomputer may
be linked to whatever means of synchronization presently exists. For example, a glass
forming machine operates at a much slower speed for large articles of glassware than
for smaller articles of glassware. The operation of the various components also must
be slower. This could be accomplished in the present invention by either completely
changing the X and Y ramp tables for different sizes of glassware and providing different
rate bits , or the speed of the loop which determines the time period for a rate bit
could be changed. As the speed of the glass machine increases, the time period for
a single loop or the time which is accorded a single rate bit, could also decrease.
This could be simply accomplished by defining the speed of the loop by reference to
the period between pulses from the pulse generator or other synchronization means.
[0055] For example, an interrupt timer 68 (Figure 5) could be provided to interrupt the
program on a frequent basis between the rising edge of two pulses from the pulse generator
or other synchronization means and go to a subroutine which would increment a binary
counter during the interrupt. The binary counter would then provide an indication
of the frequency of the pulse generator. This binary counter could then be used to
provide the frequency of the loop routine in the main program with respect to the
rate bits. For example, if the -machine speed is relatively slow as with large glass
articles, the pulses from the pulse generator will have relatively large periods between
them. The binary counter initiated by the interrupt timer subroutine would count a
relatively large number between pulses. The number accumulated in the binary counter
would be used to provide a relatively slow frequency of looping in the portion of
the - program which provides for looping the number of times indicated by the rate
bits. This would provide a direct link between the machine speed and the various component
speeds and allow an optimized X or Y data table to be used on a variety of glassware
production at different speeds. It would also be possible to provide each individual
function microcomputer with a number of separate data tables which could be appropriately
selected from the central control unit. Different data tables could also be available
for starting and stopping the machine and/or for emergency stopping of the machine.
[0056] In the high-speed production of certain ware it may be desirable to gradually slow
certain components to a stop in emergency situations or other situations where the
present controllers stop sending an actuation signal in the middle of a component's
motion envelope. The preferred embodiment of the subject invention, as above described,
would immediately stop a component upon ceasing to receive an actuation signal from
the electronic control unit. Where the component is one which is presently under only
a single mode of electronic control, the subject invention, in addition to immediately
stopping the component upon ceasing to receive an actuation signal, would reverse
the direction of the component immediately. The extra acceleration which the component
and any ware in the component would undergo in such transitions may be unacceptable
under some circumstances. This can be easily remedied by providing a test of the rate
bit number pointed to at each instance such a transition is initiated. If the number
is greater than a predetermined safe magnitude, the component can be safely stopped
as a relatively high magnitude rate bit number would indi
- cate slow speed. If the rate bit number is below said predetermined safe magnitude,
a subroutine could be entered which would utilize the existing number and increase
it by predetermined amounts, executing the step in movement for each increase, until
the predetermined safe magnitude of rate bit is reached thereby slowly. decelerating
the component. The subroutine would also keep track of the steps necessary to perform
the stop and could then move the com: ponent back to the step last pointed to in the
tables at the time the stop or change in direction is initiated. Alternatively, the
subroutine could -increment the ramp tables, although not using the data, so that
the words in the rate table which are pointed to correspond to the appropriate resting
position of the component. A similar subroutine could be used at anytime motion of
a component is to be initiated from a position other than at the beginning of the
appropriate rate table, for example after an emergency stop. Upon receiving an actuation
signal a test would be performed to determine if the pointed to rate bit was smaller
than a predetermined safe magnitude. If the number were larger than the predetermined
safe magnitude, the component's motion would be initiated in accordance with the ramp
table. If the rate number were smaller than said predetermined safe magnitude, an
initial calculation would be performed to determine the number of steps necessary
to safely achieve the speed corresponding to the pointed to rate bit number. The component
would then be driven in reverse, the number of steps so determined and gradually accelerated
in the correct direction with control being turned back over to the ramp table at
the appropriate step.
[0057] In its broadest aspects, the present invention contemplates a method and apparatus
for precisely controlling the motion of at least one of the components in a glass-forming
machine by mechanically linking said component to a digitally responsive motor module,
providing data corresponding to the desired motion of said component in a first storage
means, and controlling the motion of said component through a component controller
connected to said storage means and said digitally responsive motor module. In the
preferred embodiment said data comprises a ramp table having a dedicated data grouping
for each increment of movement of said component, said grouping including an indication
of the direction of movement of said component, whether said component is at the beginning
or end of a motion envelope, and the time period for an increment of movement of said
component. A refinement to said invention is the ability to utilize an optimized data
table for a component over a variety of machine speeds by linking the time period
defined by said data grouping to the machine speed. A further refinement is the elimination
of excessive accelerations of said components when emergency stopping the glass-forming
machine. The preferred embodiment is compatible with the majority of presently available
electronic controllers used in the glass-forming industry with minimum modification.
1. In a glassware forming machine having a plurality of components which cyclically
move in synchronized concert, the improvement of an apparatus for precise control
over the motion envelope of at least one of said components, comprising:
a digitally responsive motor module for driving said component; -
a first storage means for storing data corresponding to a first desired motion envelope
of said component; and
means for controlling said digitally responsive motor module in accordance with said
stored data.
2. The apparatus of Claim 1 wherein said first storage means' includes a data table
having an identified location for each unit movement of said digitally responsive
motor module.
3. The apparatus of Claim 2 wherein each of said identified locations in said data
table includes data indicative of the relative time between a unit movement of said
digitally responsive motor module.
4. The apparatus of Claim 3 wherein each of said identified locations in said data
table corresponding to a unit movement of said digitally responsive motor module includes
data indicative of the direction of said movement.
5. The apparatus of Claim 4 wherein said means for controlling said digitally responsive
motor module. is an individual function microcomputer.
6. The apparatus of Claim 1 including a means for altering said data corresponding
to a first desired motion envelope of said component to provide data in said first
storage means corresponding to a second desired motion envelope of said component.
7. The apparatus of Claim 6 including a second storage means for storing data corresponding
to a plurality of different motion envelopes of said component.
8. The apparatus of Claim 7 including a means for communicating data from said second
storage means to said first storage means.
9. An apparatus for controlling a glassware forming machine having a plurality of
components which cyclically move in synchronized concert, at least some of said components
having programmable motion envelopes comprising:
means for providing a signal in synchronism with the operation of said machine;
storage means for storing the relative times in a cycle of operation when each of
the plurality of components is to be actuated and for storing data corresponding to
desired motion envelopes for said components; . -
means connected to said signal providing means and said storage means for outputting
an actuation signal to one of sa5d components when its respective relative time in
the cycle of operation is reached;
digitally responsive motor modules for driving said components having programmable
motion envelopes; and
component control means connected to said storage means and said digitally responsive
motor modules for, upon receiving an actuation signal, controlling said digitally
responsive motor modules in accordance with said stored data.
10. The apparatus of Claim 9 wherein said data is arranged in tables having locations
for each unit movement of said digitally responsive motor modules.
11. The apparatus of Claim 10 wherein said data includes rate numbers which are indicative
of the time period of said unit movement of said motor modules.
12. The apparatus of Claim 11 including means for timing said signal in synchronism
with operation of said machine and means for altering said rate numbers upon change
of said frequency.
13. The apparatus of Claim 12 wherein said component control means includes an individual
function microcomputer and memory for each of said components having programmable
motion envelopes.
14. In a glass forming machine having a plurality of components which cyclically move
in synchronized concert, a method of precisely controlling the motion envelope of
at least one of said components, comprising the steps of:
driving said component with a digitally responsive motor module;
storing data corresponding to the desired motion envelope of said component in a first
storage means; and
controlling the motion of said component in accordance with said data.
15. The method of Claim 14 wherein said data includes a plurality of successive data
units, each data unit corresponding to a unit movement of said component.
16. The method of Claim 15 wherein each of said data units includes a directional
indicator and a rate indicator; and said controlling step includes testing said data
unit for direction, outputting a signal for a unit movement of said digitally responsive
motor module in accordance with said directional indicator, delaying further operation
of said digitally responsive motor in accordance with said rate indicator, and repeating
said testing, outputting and delaying steps for subsequent data units.
17. In a machine having a plurality of cyclically moving components which operate
in a timed relationship with respect to one another, a method of precisely controlling
the motion of at least one said components comprising:
formulating a ramp-on and a ramp-off function for said component;
storing said formulated function in a mass storage device;
controlling the movement of said component with a component controller;
loading the ramp-on and ramp-off function for each component into an individual memory
associated with the respective component controller; and
when actuated, moving the component in accordance with said ramp functions.
18. A method of operating a glassware forming machine having a plurality of components
which cyclically move in synchronized concert, at least some of said components being
critically controlled within narrow motion envelopes, comprising the steps of:
providing a timing signal which is synchronized to the cyclic operation of the machine;
storing the relative actuation times in the cycle for the various components in a
memory means;
generating an actuation signal when the actuation time of. a component is reached;
mechanically linking said critically controlled components to a digitally responsive
motor module;
storing a ramping function which defines said narrow motion envelope of said digitally
responsive motor module; and-
when actuated, moving said critically controlled component in accordance with said
ramping function.
19. The method of Claim 18 including determining the speed of said cyclic operation
through said timing signal and altering said ramping function in accordance with changes
in said speed.